Standby

n. one who is dependable and reliable in emergencies; something which can be relied upon; person or thing that serves as a substitute; (Travel) passenger who has no reservation, passenger who must wait for an available unreserved seat; (Travel) ticket without a prior reservation on any public transportation (airplane, train, etc.)

adj. ready for use in the event of sudden need or emergency; of or pertaining to the condition of standing by

Standby may refer to:Standby (telecommunications), term in telecommunicationsStandby (air travel), a list in which passengers may request to be placed on to request an earlier or more convenient flight.Standby (theater), an actor or performer who will appear in a particular role if the regular performer is not present – similar to an  understudy. However, unlike understudies, standbys will only perform when they are needed to cover a role, and do not regularly appear in a show.Standby (band), a hard rock band from Sweden.Standby (electricity) or standby mode - a mode in which electronic appliances are turned off but under power and ready to activate on commandStandby (computers), a mode an ACPI-compliant computer can be in. It is more formally called ACPI S3.Standby, the term NASA uses in air-to-ground radio communications for expressing "please wait"
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Noun
1. something that can be relied on when needed
(hypernym) thing
(derivation) stand by, stick around, stick about
2. an actor able to replace a regular performer when required
(synonym) understudy
(hypernym) actor, histrion, player, thespian, role player
(derivation) stand by, stick around, stick about
Adjective
1. ready for emergency use; "a standby generator"; "a standby crew"
(similar) secondary

n. standby, standby position

1. In computer and communications systems operations, pertaining to a power-saving condition or status of operation of equipment that is ready for use but not in use. Note: An example of a standby condition is a radio station operating condition in which the operator can receive but is not transmitting. 2. Pertaining to a dormant operating condition or state of a system or equipment that permits complete resumption of operation in a stable state within a short time. 3. Pertaining to spare equipment that is placed in operation only when other, in-use equipment becomes inoperative. Note: Standby equipment is usually classified as (a) hot standby equipment, which is warmed up, i.e., powered and ready for immediate service, and which may be switched into service automatically upon detection of a failure in the regular equipment, or (b) cold standby equipment, which is turned off or not connected to a primary power source, and which must be placed into service manually.